Monday, 20 April 2015

There was an interesting exchange last week on PubMedCommons between Maurice Smith, senior author of a paper on motor learning, and
Bjorn Brembs, a neurobiologist at the University of Regensburg. The main thrust
of Brembs' critique was that the paper, which was presented as surprising,
novel and original, failed adequately to cite the prior literature. I was
impressed that Smith engaged seriously with the criticism, writing a reasoned
defence of the choice of material in the literature review, and noting that
claims of over-hyped statements were based on selective citation.What really caught my attention was the
following statement in his rebuttal: "We
can reassure the reader that it was very painful to cut down the discussion,
introduction, and citations to conform to Nature Neuroscience’s strict and
rather arbitrary limits. We would personally be in favor of expanding these
limits, or doing away with them entirely, but this is not our choice to make."

As it happens, this comment really struck home with me, as I
had been internally grumbling about this very issue after a weekend of serious
reading of background papers for a grant proposal I am preparing. I repeatedly
found evidence that length limits were having a detrimental effect on
scientific reporting. I think there are three problems here.

1. The first is exemplified by the debate around the motor
learning paper. I don't know this area well enough to evaluate whether
omissions in the literature review were serious, but I am all too familiar with
papers in my own area where a brief introduction skates over the surface of
past work. One feels that length limits play a big part in this but there is
also another dimension: To some editors and reviewers, a paper that starts
documenting how the research builds on prior work is at risk of being seen as
merely 'incremental', rather than 'groundbreaking'. I was once explicitly told
by an editor that too high a proportion of my references were more than five
years old. This obsession with novelty is in danger of encouraging scientists to
devalue serious scholarship as they zoom off to find the latest hot topic.

2. In many journals, key details of methods are relegated to
a supplement, or worse still, omitted altogether. I know that many people
rejoiced when the Journal of
Neuroscience declared it would no longer publish supplementary material: I
thought it was a terrible decision. In most of the papers I read, the methodological
detail is key to evaluating the science, and if we only get the cover story of
the research, we can be seriously misled. Yes, it can be tedious to wade
through supplementary material, but if it is not available, how do we know the
work is sound?

3. The final issue concerns readability. One justification
for strict length limits is that it is supposed to benefit readers if the
authors write succinctly, without rambling on for pages and pages. And we know that the longer the paper, the
fewer people will even begin to read it, let alone get to the end. So, in
principle, length limits should help. But in practice they often achieve the
opposite effect, especially if we have papers reporting several experiments and
using complex methods. For instance, I recently read a paper that reported, all
within the space of a single Results section about 2000 words long, (a) a
genetic association analysis; (b) replications of the association analysis on
five independent samples (c) a study of methylation patterns; (d) a gene
expression study in mice; and (e) a gene expression study in human brains. The
authors had done their best to squeeze in all essential detail, though some was
relegated to supplemental material, but the net result was that I came away
feeling as if I had been hit around the head by a baseball bat. My sense was
that the appropriate format for reporting such a study would have been a
monograph, where each component of the study could be given a chapter, but of course,
that would not have the kudos of a publication in a high impact journal, and
arguably fewer people would read it.

Now that journals are becoming online-only, a major reason
for imposing length limits – cost of physical production and distribution of a
paper journal – is far less relevant. Yes, we should encourage authors to be
succinct, but not so succinct that scientific communication is compromised.